1. Field
This disclosure relates generally to memories, and more specifically, to ternary content addressable memory (TCAM) with programmable resistive elements.
2. Related Art
A content addressable memory (CAM) is a type of memory that is typically used in high-speed search operations. For a search operation, a CAM compares input search data against a table including rows of stored data, and returns the address of the matching data. Two basic types of CAMs include a binary CAM (BCAM) and a ternary CAM (TCAM). In a BCAM, each bitcell stores one of two data states, a logic “1” or a logic “0”, such that the input search data is compared with each row of the BCAM to determine whether the stored data of the row matches the input search data. In a TCAM, each bitcell stores one of three data states, a logic “1”, a logic “0”, or a “don't care” value, in that the “don't care” value results in a match of the bit regardless of the value of the input bit of the search data. In order to encode three data states, each TCAM bitcell is configured to store two bits.
The present invention is illustrated by way of example and is not limited by the accompanying figures, in which like references indicate similar elements, unless otherwise noted. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale.